Well that's cool, personally i wasn't alive in those days :)
On another note, the absolute best mail client i have ever used is FairEmail on android. It even beats Thunderbird on the desktop. If you run android i highly recommend that too.
Ha! My Unix timeline history is vague now but I’ve used SCO, DG/UX and HP/UX in anger. Pretty sure mailx was my client on most of those! :) (not to mention SunOS and Sequent at some point. And DRS/NX. But that’s not one to mention in polite company)